In recent years, power devices which have a high breakdown voltage performance and which are used in applications handling large electric currents have been actively developed. In the development of such power devices, nitride semiconductors which are materials which have a high dielectric breakdown electric field and a high saturated electron speed have recently attracted attention. Among these, GaN power devices which use gallium nitride (GaN) are expected to greatly contribute to energy saving in low loss and high speed power switching systems in the future.
In a case of using blade dicing which is generally used for silicon in the manufacturing of the GaN power device described above, since a GaN film is harder than silicon and nitride semiconductors such as GaN and silicon have different lattice constants, thermal expansion coefficients, and the like, a large amount of stress is generated in the vicinity of the interface between the silicon substrate and the GaN film at the time of dicing. Then, when a mechanical shock due to the dicing is imparted to a region in which stress is generated in the vicinity of the interface, cracks or the like are generated starting from the vicinity of the interface. In order to solve this problem, for example, laser dicing is used.
A semiconductor wafer in the prior art which uses laser dicing is, for example, described in Japanese Unexamined Patent Application Publication No. 2006-222258 (PTL 1). In the semiconductor wafer in the prior art, the semiconductor wafer is cut by combining laser dicing and blade dicing.